This is a simple Objective C program written to check whether a number is a Prime number.
//
// main.m
// PrimeNumbers
//
// Created by Ravi Shankar on 10/02/12.
// Copyright (c) 2012 rshankar.com. All rights reserved.
//
#import <Foundation/Foundation.h>
int main (int argc, const char * argv[])
{
@autoreleasepool {
int number;
BOOL isPrime=YES;
NSLog (@”Enter a number”);
scanf(“%i”,&number);
for (int i=2; i < number –1; i++)
{
if (number % i == 0)
{
isPrime = NO;
break;
}
}
if (isPrime)
{
NSLog (@”%i is a Prime Number”,number);
}
else
{
NSLog (@”%i is not a Prime Number”, number);
}
}
return 0;
}
Output (as displayed in Xcode console window)
2012-02-10 15:53:52.072 PrimeNumbers[1164:707] Enter a number
23
2012-02-10 15:53:58.665 PrimeNumbers[1164:707] 23 is a Prime Number
2012-02-10 15:54:41.469 PrimeNumbers[1176:707] Enter a number
24
2012-02-10 15:54:44.589 PrimeNumbers[1176:707] 24 is not a Prime Number
This program checks whether the number is divisible by any of the n-1 number and if divisible (% operator returns reminder as 0) then the flag is set to false otherwise it is set to true. Then based on the flag value the message is printed to the console window.